Tuesday, November 20, 2012

The Microphone: High Fidelity Audio’s Final Frontier?

Though a topic more likely to be discussed and reviewed in a professional-audio magazine than in a hi-fi magazine does the microphone truly represent the final frontier in our pursuit of high fidelity sound?

By: Ringo Bones

During the Golden Age of Stereo, all audio recording equipment – even one’s destined for domestic use – were all equipped with microphone inputs to facilitate do-it-yourself recording for the audio enthusiast. And as time went on – as in around the 1980s, every audio recording gear destined for consumer/ domestic use – like hi-fi cassette tape decks and later recordable CD decks, mini disc, DCC and even DATs – seem to forego the inclusion of a microphone input as a feature. Given that virtually all music and audio recording that we will eventually be listening to our home audio gear was first captured by microphones, does the microphone truly represent the final frontier in our quest for high fidelity sound that’s indistinguishable from the one that occurs naturally? Or does existing microphone technology actually “hear” music the way our ears do?  

As stated by Stereophile magazine editor John Atkinson during the recording of their Encore CD in the January 1998 issue of their magazine, there is absolutely nothing natural about recording an acoustic event – let alone making it sound as natural as possible. As a testament as being the engineer of the scores of recordings commissioned and sold in Stereophile, Atkinson – and probably every other experienced recording engineer like him – is ready to admit that microphones don’t “hear” music in the same way that our ears do. And far from being natural, are actually chosen for their sound during sound recording / music recording.

As an example in the live Classical Music recording session world – if one is recording violins, the polar distribution of the radiated power along the axis of the violins’ top plates is such that it will overwhelm any other sounds the microphones are intended to record – so one is forced to record from any position but one along that axis. Most recording engineers choose to raise their microphones well above it since that solves other problems relating to the way microphones perceive – or “hear” - the musical instruments on a performing stage.

To cite Atkinson’s another example: Simply by using spaced omni-directional microphones, a recording engineer can create an illusion of spaciousness that may not truly exist in the recording venue. The distance between the microphones affects lateral time cues on the recording; the perception of spaciousness can be profoundly influenced simply by varying that spacing.

The rather novel microphone setup known for its unrivaled naturalness in capturing the sound of the recording venue used by John Atkinson on all of the Stereophile live music recordings made in the 1990s are compared to “multi-way speakers” by other recording engineers since the microphone setup is optimized to pickup either the lower or the upper part of the audible spectrum. They consist of two outrigger B&K omnis that were hung by their leads from the ceiling 8-feet from the stage and 13-feet from the floor. A central pair of B&K cardioid microphones was mounted on a stereo bar, and hung by their leads from the center of the ceiling 11-feet above the level of the stage and the same 8-feet back the omnis. The two cardioids were used in what is called an ORTF configuration: the mikes angled at 115-degrees, their tips spaced about 7-feet apart. The ORTF microphone technique was developed in France and gives a nicely defined soundstage, but the tonal balance lacks low-frequency bloom. The spaced omnis, on the other hand, give a wonderful sense of bloom and very accurate tonal color, but have mediocre stereo imaging. Such rather elaborate setup results in a Classical Music recording that has the sound-staging of a minimally-miked recording with a tonal naturalness of a multi-miked recording.

Unfortunately, such recording set-up that works very well in the Classical Music recording world doesn’t work very well in the heavy metal / rock world – which requires quite a different microphone, recording  and mixing set-up altogether. One of the problems is purely technical: To create a clean heavy metal / rock recording with excruciatingly loud electric guitars is extremely difficult when the guitar amps, the drum kit, and the vocalist via a loud PA system used as a monitor are all going at the same time in the same room / acoustically unisolated recording venue.

 Because the sound of the instruments leaks into the microphones used to record the sounds of the other instruments, a muddy sound is the result. Given that most bootleg heavy metal / rock concert recordings made from the 1970s and the 1980s have their sound captured by a microphone set up that resembles the one intended for minimally miked Classical Music recording, most bootleg heavy metal / rock recordings tend to be unbearably muddy sounding in comparison to their studio recorded counterparts – or a live concert recording “overseen” by a skillful FOH mixing engineer. In conclusion, we still need skillful live music recording engineers / FOH mixing engineers to make existing microphone technology sound as natural as the way our own two ears hear music – whether Classical or heavy metal rock.


VaneSSa said...

Ah, the trusty Brüel & Kjaer Microphone in ORTF configuration as used by Stereophile in their exemplary CD releases back in the 1990s. Current sound and music recording process / reproduction technology - especially in the "purist" Classical Music Recording world all the way to the reproduction (our home hi-fi rigs) chain - cannot yet accurately reproduce the unamplified sound of string instruments in general, and violins in particular in forte volume passages or louder. While in the Heavy Metal Rock recording world - the skillful knob twiddling and an ear for how loud amplified guitars, basses and drums sound in real life by the recording engineer / FOH engineer, is primarily what makes "most" Heavy Metal Rock recordings sound much closer to the real live event compared to purist Classical Music recording. I mean have you ever heard an LP or 16-Bit 44.1-KHz sampled CD that "accurately" rendered the sound of a Classical Music string quartet playing forte or louder?

Ringo said...

After recently "unearthing" the old issues of Stereophile magazines in our local public library, Vanessa, I just found out that Lewis Lipnick - at one time Stereophile's Musician-In-Residence - attacked the microphone back in the early 1990s as perhaps one of the weakest links in the audio chain. Lipnick stated in Stereophile of how rare it is to see any published frequency-response graphs of the majority of microphones being sold in the professional audio / pro-audio market. Unfortunately back then, Lewis Lipnick never got the chance to call upon microphone manufacturers to launch an all-out research and development program. Furthermore, I do not recall any audio publication - including pro-audio ones like Mix and EQ, etc. - that has ever called for such an Rn'D program even until this day. Major microphone manufacturers should launch an all-out Rn'D program to improve the timbral accuracy of their microphones because after all, don't we audiophiles all want for recorded musical instruments - especially the drum kit - and singers' voices to sound as close as possible to the real thing?